OK, so the end of s4 was one of the TV moments of the last view years. An absolutely fantastic coming together of plot, themes, visuals, the lot. It gives the impression, and I don't know whether they intended this or have just been very lucky, or what, but it's as if they wrote all 46 episodes just to get to that point, because everything harmonises. Some of the most ambitious and satisfying telly I think I've ever seen.